{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

# mse06 - Chapter 6 Mechanical Properties ISSUES TO ADDRESS...

This preview shows pages 1–6. Sign up to view the full content.

1 Chapter 6 - 1 ISSUES TO ADDRESS. .. Stress and strain : What are they and why are they used instead of load and deformation? Elastic behavior: When loads are small, how much deformation occurs? What materials deform least? Plastic behavior: At what point does permanent deformation occur? What materials are most resistant to permanent deformation? Toughness and ductility : What are they and how do we measure them? Chapter 6: Mechanical Properties Chapter 6 - 2 Elastic means reversible ! Elastic Deformation 1. Initial 2. Small load 3. Unload F δ bonds stretch return to initial F δ Linear- elastic Non-Linear- elastic

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
2 Chapter 6 - 3 Plastic means permanent ! Plastic Deformation (Metals) F δ linear elastic linear elastic δ plastic 1. Initial 2. Small load 3. Unload planes still sheared F δ elastic + plastic bonds stretch & planes shear δ plastic Chapter 6 - 4 Stress has units: N/m 2 or lb f /in 2 Engineering Stress Shear stress, τ : Area, A F t F t F s F F F s τ = F s A o Tensile stress, σ : original area before loading Area, A F t F t σ = F t A o 2 f 2 m N or in lb =
3 Chapter 6 - 5 Simple tension: cable τ Note: τ = M / A c R here. Common States of Stress A o = cross sectional area (when unloaded) F F o σ = F A o τ = F s A σ σ M M A o 2 R F s A c Torsion (a form of shear): drive shaft Ski lift (photo courtesy P.M. Anderson) Chapter 6 - 6 (photo courtesy P.M. Anderson) Canyon Bridge, Los Alamos, NM o σ = F A Simple compression: Note: compressive structure member ( σ < 0 here). (photo courtesy P.M. Anderson) OTHER COMMON STRESS STATES (1) A o Balanced Rock, Arches National Park

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
4 Chapter 6 - 7 Bi-axial tension: Hydrostatic compression: Pressurized tank σ < 0 h (photo courtesy P.M. Anderson) (photo courtesy P.M. Anderson) OTHER COMMON STRESS STATES (2) Fish under water σ z > 0 σ θ > 0 Chapter 6 - 8 Tensile strain: Lateral strain: Shear strain: Strain is always dimensionless. Engineering Strain θ 90º 90º - θ y Δ x θ γ = Δ x / y = tan ε= δ L o δ ε L = L w o Adapted from Fig. 6.1 (a) and (c), Callister 7e. δ /2 δ L /2 L o w o
5 Chapter 6 - 9 Stress-Strain Testing • Typical tensile test machine Adapted from Fig. 6.3, Callister 7e. (Fig. 6.3 is taken from H.W. Hayden, W.G. Moffatt, and J. Wulff, The Structure and Properties of Materials , Vol. III, Mechanical Behavior , p. 2, John Wiley and Sons, New York, 1965.) specimen extensometer • Typical tensile specimen Adapted from Fig. 6.2, Callister 7e.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

### Page1 / 17

mse06 - Chapter 6 Mechanical Properties ISSUES TO ADDRESS...

This preview shows document pages 1 - 6. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online